New York, N.Y. New York University Bookstore 1943. vii, 140 ff (leaves). Stapled. Blue printed wrappers, with linen taped spine as issued. Photomechanically reproduced typescript printed on the rectos only. Very Good. Staplebound. 
Donald D. Millikin wrote a number of popular articles including "Cipher Writing" for the Encyclopedia Americana in 1937, "The Japanese Morse Telegraph Code".for QST in 1942 and "Cryptography" for the Colliers Encyclopedia in 1949. The present text was designed for classroom use, and went through several editions in 1942 and 1943. This (the third edition) appears to be the last. An original copy, this work was much later reprinted by Aegean Park Press.
While not publications that advanced mathematical theory, as an educator of young people during World War II Millikin contributed to the availablility of persons more versed in the field than they might otherwise have been. As to why do it, Millikin notes: "The literature of cryptography is extensive, but the majority of the works are in foreign languages and many publications are rare. The Scarcity of treatises in English is marked. Texts on cryptanalysis are even more rare than those dealing with cryptography. Most of them are government publications and not available to the general reader...." He also tempers the readers expectations by characterizing the work practically - a large part is luck, a lot of work is required, and while essential it is not a magical mysterious endeavor.
Galland (p 126) notes: "This text deals with the fundamentals of cryptography and cryptanalysis, and contains charts, forms, and frequency tables." Schulman (p 115) supplements this noting "...a short bibliography and data on foreign languages. Used by the author as a textbook at New York University with homework assignments printed separately. The first edition was in 1942.
Well represented in libraries but not often found in the marketplace. Much of the collecting in this field centers around theory and specific codes. This is a good opportunity to see how the basics were taught during wartime to students.
Galland, Joseph S., "An Historical and Analytical Bibliography of the Literature of Cryptology", Northwestern University: Evanston, 1945.
Schulman, David, "An Annotated Bibliography of Cryptography", Garland Publishing Inc: New York and London, 1976